The present program of research examines the role of emotional arousal in semantic processing. The proposed studies will use brain electrophysiological (ERP) measures to test hypotheses concerning the effects of positive and negative emotion on the structure (speed and scope) of semantic priming. Studies will attempt to identify electrophysiological effects associated with dimensions of semantic priming such as associative distance, using dense-array (128- and 256-channel) measures, which permit more accurate characterization of spatiotemporal patterns of electrophysiological response. Psycholinguistic manipulations will be used to assess the contributions of different mechanisms of semantic expectancy, such as automatic vs. controlled priming. In addition, psychometric assessments will allow correlation of reaction time and ERP measures (e.g., N400 latency and amplitude) with different dimensions of emotional arousal. It is predicted that positive emotion (mild elation) and negative emotion (anxiety) will lead to qualitatively different priming effects, as indexed by electrophysiological measures of semantic association, hemispheric dominance, and time course of semantic access. Within-subjects mood manipulations will be conducted, to strengthen emotion-cognition effects and to determine the relative contribution of state versus trait emotional factors. Taken together, the proposed studies would contribute significantly to our understanding of the role of emotion in semantic processing. This knowledge could lead to a richer understanding of the neural architecture that supports semantic processes, as well as conceptual changes associated with mood disorders, such as anxiety, depression, and bipolar disorder.